Cherokee89sport

In an open cooling system (The one with a rad. cap) is it normal for the overflow bottle to fill up beyond the full mark after driving it?
To my understanding, in the closed system it is.
But what about the open system?
Note: I've had very slight overheating issues

Gee oh Dee

Does it all get sucked back in?

As the fluids heat up they expand, causing them to get pushed back into the overflow. As the motor cools, the fluid gets pulled back in.

It almost sounds like you may have an air bubble in the cooling system.

Cherokee89sport

Ya it does get sucked back in
I was just wondering if that was normal, I've been around Jeeps my entire life but they were all Renix Models

94JeepCherokeeMan

X2... Liquid doesn't expand enough to do that, but air sure does.....

Rob

Cherokee89sport

Aight well how do yall get the air out in yalls?

Do yall just run it without the rad cap?

Gee oh Dee

That's one way. But special funnels are made to help out, and they really do help.

94JeepCherokeeMan

Take cap off and "burp" 'er. Takes a full minute for it to start cycling. Be forewarned: keep a damn close eye on it and kill it before it starts spraying all over everything...


Rob

Cherokee89sport

Aight thanks guys, ill probably be flushing the entire system next week, so ill just burp her when im done.

djb383

U may be getting a little hotter than u think. The whole idea behind the "open" system is to constantly eliminate any air in the system as the motor normally heats up and to replace the air with coolant as the engine cools......provided the 2-way valve in the rad cap is functioning correctly AND coolant enters/exits the bottle from the bottom AND there are no leaks (however small) in the cooling system.

I would think filling beyond the "full" mark would indicate the bottle was overfilled when the engine was cold or the engine is overheating, forcing more coolant (than normal) into the bottle.

Cherokee89sport

well the jeep only had that happen once, and it ran a little hot that day, I havn't really seen it get like that since

djb383

On our '98 there's a lot of room in the bottle above the full mark. You're probably ok as long as coolant doesn't actually flow out the top of the bottle, and onto the ground. Keep an eye on it.

Gee oh Dee

x2

Well said.

Brandon100887

I had same prob n my 89 after flushed coolant went 4x4ln and it over heated slightly came back home and burped the system of any excess air and it no longer did it or got any hotter than normal

Cherokee89sport

Thanks Guys